We applied laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy to assess the structural content of alginate solutions and gels prepared at various concentrations (1.0 to 40 mg/mL). Alginate is a natural biopolymer typically extracted from brown seaweed and has been applied in diverse biomedical applications. LIBS measurements in Alginate solutions show spectral lines that can be attributed to calcium (422.6, 393.3, and 396.8 nm), magnesium (279.5 nm), strontium (460.7 nm), and C-N bond (~388.3 nm). Crosslinking the alginate solutions into hydrogels tends to reduce emission intensity, and many LIBS lines are not discerned. Measured Raman spectra show several peaks in addition to those of water and dissolved oxygen and nitrogen. The higher the alginate concentration, the higher the intensity of the alginate peaks. We combined the intensity correlation analysis (ICA), principal component analysis, and first-order derivative method to assess changes of the Raman peaks. Altogether, the results demonstrate how both techniques can provide complementary insight for chemical analysis of alginate solutions and gels.
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